Design Guide
81
Memory Interface Routing Guidelines
6.10
DDR Signal Termination
Place a 1.25 V termination plane on the top layer just beyond the DIMM connector furthest from
the MCH on each channel, as shown in
. The VTERM island must be at least 50 mils
wide. Use this termination plane to terminate all DIMM signals, using one 22
Ω
± 2% resistor per
signal. Decouple the VTERM plane using one 0.1 µF decoupling capacitor per two termination
resistors. In addition, place one 100 µF Tantalum capacitor on each end of each termination island
for bulk decoupling. Each decoupling capacitor must have at least 2 vias between the top layer
ground fill, and the internal ground plane. Refer to
Figure 6-18. DDR VTerm Plane
One 100 µF Tantalum
Capacitor at Each End
of Each Island
DIMM8 (Furthest from MCH)
1.25V Vterm Fill
One Rtt per signal
One 0.1 µF Decoupling
Capacitor per 2 Termination
Resistors or (2 Caps/Rpack)
DIMM to Rtt
(0.8" max)
Two Vias Per 1 Capacitor
to the Internal Ground
Plane
Ground Fill on
Top Layer
DIMM7
DIMM6
50 mils
minimum
50 mils
minimum
One 0.1 µF
decoupling
capactior per 2
termination
resistors
Ground Fill
on Top Layer
1.25V
Vterm Fill
Two Vias Per 1
Capacitor to the
Internal Ground
Plane
Summary of Contents for Xeon
Page 24: ...Introduction 24 Design Guide This page is intentionally left blank ...
Page 30: ...Component Quadrant Layout 30 Design Guide This page is intentionally left blank ...
Page 52: ...Platform Clock Routing Guidelines 52 Design Guide This page is intentionally left blank ...
Page 66: ...System Bus Routing Guidelines 66 Design Guide This page is intentionally left blank ...
Page 118: ...Intel 82870P2 P64H2 118 Design Guide This page is intentionally left blank ...
Page 146: ...I O Controller Hub 146 Design Guide This page is intentionally left blank ...
Page 148: ...Debug Port 148 Design Guide This page is intentionally left blank ...
Page 210: ...Schematic Checklist 210 Design Guide This page is intentionally left blank ...
Page 220: ...Layout Checklist 220 Design Guide This page is intentionally left blank ...
Page 222: ...Schematics 222 Design Guide This page is intentionally left blank ...